Jason wrote:
On Mon, 19 May 2003 12:01:39 +0200
Michel Bardiaux <mbardiaux@xxxxxxxxxxx> wrote:
I might have to do the same, but the sheer amount of doc referred to on
the ALSA home page has dissuaded me so far. Can anyone tell me what is
the *minimal* software to install, and the minimal documentation set to
read, in order to convert a *working* OSS sound capture app to ALSA?
I agree. The best document that I found on there was to go to the
SoundCard matrix (click SoundCards on the main page then SOundCard Matrix)
and then click on the Details link for your specific card. At least for
mine (intel8x0), there was a nice summarized document with a quickstart
guide. Also, I am using Debian and it too had a nice quickstart guide. As
far as your sound capture app goes, you shouldn't need to change anything
once you get the OSS emulation working in ALSA (although in time, you may
want to configure it to use ALSA directly).
My reason for going to ALSO would not be a lack of OSS driver, but the
possibility of getting accurate timestamps on each and every sample. If
I cant have it in native OSS, it is unlikely I could have it in emulated
OSS.
Exactly similar, no, if only cuz we used ffmpeg first, a homegrown app
later, rather than mencoder. But there was a lot of hair tearing and
teeth gnawing here until we understood that the mixer *on the sound
card* also played its role. You can adjust it with xmixer (part of the
mctools-lite package), then check your settings with 'record' (part of
the xawtv package).
Thanks for the hint. With record, I can clearly see my problem. The
output of my TV Card (ATI TV Wonder VE) is way too low (the left&right
peeking at around 9000). Of course, I can adjust my igain too increase
that but it seems to be increasing all the noise too. What I am wondering
is, is there a way to increase the volume right at the source (the TV
Card) instead of using the Input gain of my sound card?
On some TV cards you can (reportedly), on others not (none of the 3 we
have tried). I do a VIDIOCGAUDIO and look at the VIDEO_AUDIO_VOLUME flag.
I also got the feeling (but no hard data) that with *some* sound cards,
the LINE input can be more noisy than MIKE.
How do you set the sound sampling frequency?
I tried the Mic input and it is definitely better, especially with the Mic
Boost. BUT I still am getting the high pitch 'ringing' sound in the
background. I am starting to think this just might be noise generated by
the computer itself such as the fans inside the box or something else. It
isn't like this is a high quality card as far as sound goes so I am almost
guessing I might just be stuck with it.
Jason
You could try several things: put the soundcard in another PC if you
have one; play with xmixer and see how mixer settings affect the volume
of that noise; make a spectrgogram of the noise. All this with the
highest possible sampling frequency of course.
HaND,
--
Michel Bardiaux
Peaktime Belgium S.A. Bd. du Souverain, 191 B-1160 Bruxelles
Tel : +32 2 790.29.41
